AMSR-E观测资料干扰对反演地表参数的影响

针对星载微波成像仪低频窗区通道观测数据中存在大范围无线电频率干扰(简称RFI)的情况,以微波扫描辐射计(AMSR-E)为例,首先用改进的主成分分析方法对RFI进行识别;进而探讨RFI存在对反演地表参数的影响.然后,利用经过线性拟合RFI订正后的AMSR-E观测资料,采用一维变分1D-Var方法进行地表参数反演,通过对美国地区陆地RFI订正前、后地表反演产品(地表温度及降水率)的比较,发现RFI干扰使得受影响区域反演的地表温度及降水率异常偏高,存在较大误差.因此,在使用星载微波成像仪低频窗区通道观测进行地表参数反演和资料同化前必须进行有效地RFI识别和订正,改进的主成分分析识别方法和线性拟合的RFI订正算法对陆地上观测是有效的.     

Roads,Interrupted Dispersal,and Genetic Diversity in Timber Rattlesnakes

Abstract: Anthropogenic habitat modification often creates barriers to animal movement, transforming formerly contiguous habitat into a patchwork of habitat islands with low connectivity. Roadways are a feature of most landscapes that can act as barriers or filters to migration among local populations. Even small and recently constructed roads can have a significant impact on population genetic structure of some species, but not others. We developed a research approach that combines fine‐scale molecular genetics with behavioral and ecological data to understand the impacts of roads on population structure and connectivity. We used microsatellite markers to characterize genetic variation within and among populations of timber rattlesnakes (Crotalus horridus) occupying communal hibernacula (dens) in regions bisected by roadways. We examined the impact of roads on seasonal migration, genetic diversity, and gene flow among populations. Snakes in hibernacula isolated by roads had significantly lower genetic diversity and higher genetic differentiation than snakes in hibernacula in contiguous habitat. Genetic‐assignment analyses revealed that interruption to seasonal migration was the mechanism underlying these patterns. Our results underscore the sizeable impact of roads on this species, despite their relatively recent construction at our study sites (7 to 10 generations of rattlesnakes), the utility of population genetics for studies of road ecology, and the need for mitigating effects of roads.     

杀菌剂叶青双在水中的降解特性研究

提出了一种检测水中叶青双及其降解物２－氨基－５－巯基－１,３,４－噻二唑的反相高效液相色谱分析法,进行了叶青双的水解、光解以及池塘水中自然降解的模拟试验。研究表明：叶青双在水中降解非常快,光解是其降解的主要方式,同时水解也对叶青双的降解有很大贡献。从叶青双的主要降解产物在水中的光解以及叶青双在自然池塘中模拟试验来看,叶青双的降解产物在水中也不稳定。由此得出叶青双在稻区正常使用情况下,不会对水环境及鱼类构成威胁的结论。     

Photo-Induced OH reactions of naphthalene and its oxidation products on SiO2

The photo-induced degradation of naphthalene, 1,4-naphthoquinone, 1-naphthol and 1-NO₂ naphthalene, adsorbed on silica gel, and with the addition of nitrogenous air pollutants e.g. NO₂ (as KNO₂) was investigated. Results indicate that compounds adsorbed onto a solid carrier are degraded when irradiated with UV light (λ > 290 nm) in the presence of nitrites. The key species initiating the naphthalene degradation is the OH-radical which is generated through the photolysis of NO₂. Reaction products identified were 2-formyl-cinnamaldehyde, 1,4-naphthoquinone, nitronaphthol, o-phthaldialdehyde, phthalide and nitronaphthalene. A mass balance between 40–50% was achieved. Under the same irradiation conditions, 1-NO₂ naphthalene is mainly degraded by direct photolysis while degradation of 1-naphthol and 1,4-naphthoquinone proceeds via the reaction with OH-radicals. Identified products were hydroxy-nitro-nitroso- and quinones compounds.     

O(~1D)与CF_2CIBr的反应研究

本文研究了CF_2ClBr-O_3体系在253.7nm紫外光照下所引发的O(~1D)与CF_2ClBr的反应.O(~1D)与CF_2ClBr反应的最终产物为CF_2O,Cl_2,Br_2;实验中得到O(~1D)与CF_2ClBr的反应速率常数为1.01×10~(-10)cm~3·molecule~(-1)·s~(-1),并且对O(~3P)与CF_2ClBr的反应可能性以及 O(~1D)与CF_2ClBr的反应机理进行了讨论.     

Evaluation of 1,4-naphthoquinone derivatives as antibacterial agents: activity and mechanistic studies

● All 1,4-naphthoquinone hybrids exhibited significant antimicrobial activity. ● Presence of a hydroxyl group on aromatic B-ring of juglone was crucial for activity. ● Juglone can cause DNA damage by producing ROS and downregulation of RecA. ● Juglone has the potential to become a disinfectant. The diverse and large-scale application of disinfectants posed potential health risks and caused ecological damage during the 2019-nCoV pandemic, thereby increasing the demands for the development of disinfectants based on natural products, with low health risks and low aquatic toxicity. In the present study, a few natural naphthoquinones and their derivatives bearing the 1,4-naphthoquinone skeleton were synthesized, and their antibacterial activity against selected bacterial strains was evaluated. In vitro antibacterial activities of the compounds were investigated against Escherichia coli and Staphylococcus aureus. Under the minimum inhibitory concentration (MIC) of ≤ 0.125 μmol/L for juglone (1a), 5,8-dimethoxy-1,4-naphthoquinone (1f), and 7-methyl-5-acetoxy-1,4-naphthoquinone (3c), a strong antibacterial activity against S. aureus was observed. All 1,4-naphthoquinone derivatives exhibited a strong antibacterial activity, with MIC values ranging between 15.625 and 500 μmol/L and EC₅₀ values ranging between 10.56 and 248.42 μmol/L. Most of the synthesized compounds exhibited strong antibacterial activities against S. aureus. Among these compounds, juglone (1a) showed the strongest antibacterial activity. The results from mechanistic investigations indicated that juglone, a natural naphthoquinone, caused cell death by inducing reactive oxygen species production in bacterial cells, leading to DNA damage. In addition, juglone could reduce the self-repair ability of bacterial DNA by inhibiting RecA expression. In addition to having a potent antibacterial activity, juglone exhibited low cytotoxicity in cell-based investigations. In conclusion, juglone is a strong antibacterial agent with low toxicity, indicating that its application as a bactericidal agent may be associated with low health risks and aquatic toxicity.     

以TEOS为硅源的聚硅氯化铝中铝及硅形态分布

以正硅酸乙酯 (TEOS)为硅源 ,合成了新型的聚硅氯化铝 (PASC) ,利用Al Ferron逐时络合比色法和Si Mo逐时络合比色法分别研究了其Al形态及Si形态分布 ,并与常规方法 (以硅酸钠为硅源 )合成的聚硅氯化铝做了比较 .实验结果表明 ,新方法合成的PASC具有铝硅分布均匀 ,分子量较大 ,产品重现性好的优点 .两种方法合成的PASC具有相同的Al形态分布规律 ,即高分子量Al形态含量随B值 (碱化度 )和Si Al摩尔比的增大而增加 ,Al形态随Si Al摩尔比的变化程度随B值的增大而增大 .另外通过新方法发现 ,Si形态分布也具有规律性并和Al形态具有相似的分布特征 ,但Si形态随Si Al摩尔比的变化程度随B值的增大而减小 .     

化工园区企业危险量计算模型研究

提出化工园区的危险量并探讨其含义。选择基础危险量计算模型及安全评估指标,建立化工园区企业基础危险量计算模型。通过对影响化工园区企业安全的因素进行筛选,建立企业危险量影响因素体系。在此基础上,运用改进G1法和模糊综合评价法确定各因素的权重和隶属度,对化工园区企业基础危险量模型进行改进,提出化工园区企业危险量和园区总体危险量的计算模型。实现了化工园区危险程度的量化,进而辅助化工园区的安全管理和安全规划。     

基于G_1法的飞行疲劳综合评价指标体系研究

为综合控制并评价飞行疲劳风险,通过对疲劳影响因素的深入分析,运用层次分析法(AHP)确定疲劳风险评价指标,依据G1法编制专家调查问卷,采用专家独立调查方法对指标进行判断,根据G1法确定各指标权重,建立飞行疲劳综合评价指标体系,实现对疲劳风险的量化综合评价。结果表明:运用G1法能有效地综合利用影响疲劳的各种信息评价飞行员的疲劳状况,该指标体系与现有控制飞行疲劳风险的影响因素吻合较好,可以作为进一步实现疲劳风险量化的基础。     

不同配比安全点火药B/KNO_3的研究

为研究可靠点燃主装药,性能稳定的B/KNO3点火药,对不同配比的B/KNO3进行配制并对其性能进行测试。不同配比B/KNO3在火焰感度、静电火花感度、撞击感度、摩擦感度4项外界刺激中,除了对撞击非常钝感之外,对其他3项外界刺激敏感。在不同比例的药中,以B/KNO3比例为50:50,粘结剂为X的药火焰感度最高,稳定性好;静电火花感度随B/KNO3中B比例提高而降低,摩擦感度随B/KNO3中B比例提高而提高,但当中B比例从40%提高到50%时,这两感度改变不多。分析得出B/KNO3比例为50:50,粘结剂为X的药满足对主装药点火可靠,稳定性好。